Lecture 38 - Virology Structure & Classification

Question 1

what 2 things does every virus have/make?

Answer 1

1. RNA and/or DNA
2. protein coat and surface proteins

Question 2

what 2 things do SOME viruses have?

Answer 2

1. internal proteins
2. lipid envelope

Question 3

what is the main difference between non-enveloped and enveloped viruses

Answer 3

non-enveloped have a protein capsid whereas enveloped viruses have a lipid-based envelope and protein capsid

Question 4

what 3 reasons are why viruses need complex structures?

Answer 4

1. host evasion
2. entry to the cell
3. replication

Question 5

what is physical risk

Answer 5

shearing of nucleic acid by mechanical forces

Question 6

what is chemical risk

Answer 6

ultraviolet radiation (sunlight) can modify or damage nucleic acids

Question 7

what is enzymatic risk

Answer 7

enzymes that breakdown nucleic acids abundant in the environment

Question 8

what determines the sensitivity to chemical inactivation. give examples.

Answer 8

viral components
primary = enveloped more labile
secondary = RNA genome more labile

Question 9

what are examples of physical inactivation of viruses

Answer 9

1. autoclaving
2. drying
3. ultraviolet

Question 10

what are the three divisions of viral shapes

Answer 10

1. icosahedral
2. helical
3. complex

Question 11

1. what is a physiochemical property?
2. what are they useful in predicting?
3. what is their disadvantage?

Answer 11

1. shared components of a viral family (genome type, structure, etc.)
2. sensitivity to disinfectants or antivirals
3. viruses with similar structures can cause widely different disease

Question 12

How are viruses classified?

Answer 12

1. physiochemical properties
2. disease and species
3. transmission

Question 13

1. what is useful when classifying viruses by disease/species?
2. what is a disadvantage?

Answer 13

1. diagnosis based on patient presentation
2. no indication of disinfectant or treatment efficacy

Question 14

1. what is useful when classifying viruses by transmission mode?
2. what is a disadvantage?

Answer 14

1. considers control of spread
2. no indication of disinfection or treatment efficacy

Question 15

what is the best (and second best) classification scheme to use for SARS-CoV-2?

Answer 15

best: physiochemical (RNA, enveloped)

2nd best: transmission (prevent spread)

Question 16

what properties do we use for physiochemical classification

Answer 16

1. virion morphology (size, shape, envelope)
2. genome (RNA vs. DNA)
3. proteins
4. replication strategy
5. physical properties (stability under different conditions)

Question 17

what is the classification scheme for physiochemical properties

Answer 17

1. family
2. genus
3. species
4. serotype
5. strain
6. isolate

Question 18

what is Baltimore classification

Answer 18

groups viruses based on genome and method of replication